1. Technical Field
The present invention relates to an inflatable vehicle occupant restraint, and more particularly to an igniter for igniting gas generating material to produce gas for inflating an inflatable vehicle occupant restraint, such as an air bag.
2. Description of the Prior Art
U.S. Pat. No. 3,211,097 discloses an igniter having an outer casing. The casing has at one end a nozzle port. An ignition material is contained within the casing. The ignition material comprises 97% lead dioxide and 3% boron. The casing also contains a booster material in the form of a grain. The booster material comprises 54% magnesium, 30% Teflon, and 16% Viton. The booster material is pressed into the grain configuration at pressures of 7,500 to 10,000 psi. A bridgewire ignites the ignition material, which, in turn, ignites the booster material. The booster material produces a flame which exits through the nozzle port and persists for 0.5 to 1.5 seconds. This is too long an igniter burn time for igniting gas generating material for inflating an inflatable vehicle occupant restraint, such as an air bag.
U.S. Pat. No. 3,904,221 discloses an igniter for igniting gas generating material for inflating an air bag. The igniter comprises an ignition tube which contains an ignition chemical composition. A platinum wire ignites the ignition chemical composition. The ignition is very rapid, occurring in a matter of milliseconds. The ignition generates a combustion gas which causes the ignition tube to rupture and some of the ignition chemical composition to disperse. The ignition chemical composition sprouts a flame to the outside of the ignition tube, which flame ignites the gas generating material. The gas generating material comprises relatively small tablets which are unlikely to fracture from rupture of the ignition tube and dispersal of the ignition chemical composition.